Field of the Invention
This invention relates to illumination and display technologies, and in particular, it relates to a light emitting device and a stage lighting system.
Description of Related Art
With the advance of semiconductor technologies and energy shortage around the world, and global warming issues, semiconductor LED (light emitting diode) light sources, due to their advantages in energy efficiency, environmental friendliness, controllable brightness and color temperature, etc., are gaining wide use in various fields and are replacing conventional light sources. In the near future, with the cost reduction and improvement in efficiency of LEDs, semiconductor LED light sources will replace conventional light sources in all fields.
FIG. 1 is a LED based light emitting device of current technology. As shown in FIG. 1, the light emitting device includes a red LED array 110, a green LED array 120 and a blue LED array 130. The lights emitted by these three LED arrays are respectively collimated by a first collimating lens array 140, a second collimating lens array 150 and a third collimating lens array 160 to incident on the X-shaped filter plates 170, and are combined by the X-shaped filter plates 170 into one light beam for output. A fly-eye lens pair 180 homogenizes the light outputted by the X-shaped filter plates 170, and the homogenized light is projected by the lens 190 to a target region.
In this light emitting device, the light emitting device consist of red, green and blue LED arrays, and the color control of the combined light is realized by controlling the drive currents of the red, green and blue primary color LEDs. Because the three primary color LEDs emit lights directly, the saturation of the monochromatic lights is very high; they can be used as light sources for stage lighting, and can meet the requirement for vivid colors for stages. However, because the number of primary colors is few, the spectrum of the combined white light is not continuous, so the color rendering index of the light emitting device is relatively low. In particular, for application environments such as a broadcasting room or for photography where the white light is required to have a color rendering index over 85, current light emitting devices cannot meet the color rendering index requirement.